node.js - Koa server crashing when returning too many data -

i developed light node web server koa. contain 3 services retrieve data mongo database, return them client.

the object returned array of json objects. can contain until 750.000 objects. 1 object looks following :

{"_id":"58a4779b783dbfa853a93e09","attributes":[{"key":"nb_mots","value":"16"},{"key":"fonction","value":"président"},{"key":"groupe_acronyme","value":"ump"}],"datatype":"deputes","date":"2007-10-23t00:00:00.000z","eventtype":"loi","actor":"bernard accoyer"}

my server runs under linux (debian, guess...).

my problem is: when want retrieve whole dataset (so 750.000 objects - using "allevents" service given below), server fails. message "killed". survey state of server using command "top". of course, %cpu goes high (between 90 & 95), %mem, nothing critical (moreover same if try retrieve less data).

any idea fix that?

code of server :

var kr = require('koa-route'); var koa = require('koa'); var app = koa(); var _ = require('lodash');  var mongoclient = require("mongodb").mongoclient;  var someeventspromise = function(datatype, number){   return new promise(function(resolve, reject){         mongoclient.connect("mongodb://localhost/eventdata", function(error, db) {         if (error){             return reject(error);         }         console.log("connecté à la base de données");          db.collection('events').find({'datatype' : datatype},{"limit": number ? number : 1000}).toarray(function(err, array)         {             console.log('returning %d objects', array.length);             db.close();             return resolve({eventsarray : array});         });     });   }); } var someevents = function * (datatype, number) {     var event = yield someeventspromise(datatype, parseint(number));     this.body = event; }  var alleventspromise = function(datatype){   return new promise(function(resolve, reject){         mongoclient.connect("mongodb://localhost/eventdata", function(error, db) {         if (error){             return reject(error);         }         console.log("connecté à la base de données");          db.collection('events').find({'datatype' : datatype}).toarray(function(err, array)         {             console.log('returning %d objects', array.length);             db.close();             return resolve({eventsarray : array});         });     });   }); } var allevents = function * (datatype) {     var event = yield alleventspromise(datatype);     this.body = event; }  var minmaxdatespromise = function (datatype) {   return new promise(function(resolve, reject){         mongoclient.connect("mongodb://localhost/eventdata", function(error, db) {         if (error){             return reject(error);         }         console.log("connecté à la base de données");          db.collection('events').find({'datatype' : datatype}, {date : 1}).toarray(function(err, array)         {             console.log('returning %d objects', array.length);             db.close();              let g = _.map(_.uniqby(array, function(d) {return d.date}), function(d) { return new date(d.date);});             console.log('mapping %d objects', g.length);              g.sort(function(a,b) { return b - ; });              let minmax = { maxdate : g[0], mindate : g[g.length - 1]};             return resolve(minmax);         });     });   }); }  var minmaxdates = function * (datatype) {     var dates = yield minmaxdatespromise(datatype)     this.body = dates; }   app.use(kr.get('/someevents/:datatype/:number', someevents)); app.use(kr.get('/allevents/:datatype', allevents)); app.use(kr.get('/minmaxdates/:datatype', minmaxdates));  app.listen(3010); 

as i'm pretty sure issue related fact have many data retrieve, tried send them through stream (instead of storing them in big array).

no luck, have issue :

error: write epipe @ exports._errnoexception (util.js:1023:11) @ writewrap.afterwrite [as oncomplete] (net.js:804:14)

my code following :

var kr = require('koa-route'); var koa = require('koa'); var app = koa(); var _ = require('lodash');  var mongoclient = require('mongodb').mongoclient;   var allevents = function * (datatype) {    var ctx = this;    var db = yield mongoclient.connect('mongodb://localhost/eventdata');   console.log("querying data " + datatype);    // collection   var col = db.collection('events');    ctx.body = col.find({'datatype' : datatype}).stream(   {        transform: function(doc) {          return json.stringify(doc);       }   }); }  app.use(kr.get('/allevents/:datatype', allevents));  app.listen(3010); 

last things : results used in c# unity script (just in case).

thanks in advance.

btw: can't retrieve less data, need of them.